(48g) Catalyst Deactivation in Hydrothermal Decarboxylation

Algae are a type of lipid rich aquatic biomass that has recently shown promise for the production of biofuels.  It’s been shown that the hydrothermal liquefaction of microalgae results in a bio-crude oil that can be potentially further upgraded to liquid hydrocarbon fuel.  The major problem with the bio-crude is the high oxygen content, and much of the oxygen is contained within the fatty acids.  The fatty acids, which result from the lipid content, are ideal candidates for upgrading because the removal of oxygen results in a long chain hydrocarbon.  Pt based catalysts have been shown to be effective decarboxylation catalysts in hydrothermal environments for upgrading saturated fatty acids such as palmitic (C16:0) and stearic (C18:0) acids, but the longevity of the catalysts have not been well studied.  This work focuses on the removal of oxygen from butyric acid using PtSn_x catalysts at 350 C and 3000 psig.  In both cases, Pt and PtSn catalysts were shown to deactivate over a 48 hour period.  The addition of Sn decreased the rate of deactivation of the catalyst and also had an effect of the selectivity for the decarboxylation product of propane from butyric acid.  The deactivation was shown to be due to a molecular poison as opposed to coking of the catalyst.